Objective: Accumulating evidence of common genetic vulnerability for bipolar disorder and schizophrenia has led to investigations of shared cognitive endophenotypes for these disorders. We examined performance of bipolar disorder and schizophrenia patients on spatial working memory (SWM) and Affective Go/No-Go (AGN) tasks, with the hypotheses that schizophrenia patients would perform worse than bipolar disorder patients on SWM, but that the two clinical groups would perform comparably on the AGN.

Methods: 22 bipolar disorder, 21 schizophrenia, and 17 healthy control participants completed the SWM and AGN tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB). SWM performance was examined with respect to “Perseverative Errors” (i.e., revisiting a spatial location where token previously found), and an index of “Strategy” (i.e., efficient search sequence). AGN performance was examined with respect to errors of omission (failing to respond), commission (erroneous response), and Reaction time (RT).

Results: On the SWM task, schizophrenia patients were significantly impaired on measures of Perseveration and Strategy compared to both bipolar disorder and healthy control participants (with mean scores of bipolar patients falling between schizophrenia and healthy controls, but not significantly different from healthy controls). On the AGN task, only one significant difference between bipolar disorder and schizophrenia was revealed, reflecting more commission errors by schizophrenia participants when shifting attention from negative or neutral stimuli to positive stimuli.

Conclusions: Distinctions between cognitive endophenotypes for schizophrenia and bipolar disorder may be reflected in perseverative responses across various executive functions, in the context of shared inhibitory dysfunction common to both disorders.